An improved phosphorus assay for oils without carcinogenic hydrazine sulfate

Abstract

An improved spectrophotometric method for phosphorus determination in oils is proposed. The proposed new method has made significant improvements in safety, sensitivity, and efficiency in comparison with the current American Oil Chemists' Society (AOCS) Official Method (Ca 12-55, corrected 1992). The AOCS method employs hydrazine sulfate as the reducing agent to generate molybdenum blue. Hydrazine sulfate is a known carcinogen in laboratory animals and a suspected human carcinogen. The chemical also irritates skin and mucous membranes. [n the improved method ascorbic acid is used as the reducing agent. Ascorbic acid is equally effective as hydrazine sulfate for the color reaction. The improved method is approximately 75 times more sensitive than the AOCS method. The sensitivity is improved by measuring absorbance at the absorption peak, 825 nm, and reducing the final volume of reaction mixture for color reaction. The AOCS method determines phosphorus by measuring absorbance at 650 nm, which is about 40% of that at the absorption peak. The efficiency of this improved method is also significantly increased by reducing sample size and the volumes of sample preparation. Therefore, the improved method is more cost-effective than the AOCS method because less chemical reagents and smaller glassware are used, and the hazardous chemical waste disposal cost is eliminated. The improved method also avoids concentrated HCI and 50% KOH for sample preparation. ]AOCS 72, 881-885 (1995).

Highly active P-doped sulfided NiMo/alumina HDS catalysts from Mo-blue by using saccharose as reducing agents precursor

“…Srinivasan et al [38] also used hydrazine-hydrochloric acid solution although in this case Mo-blue coloring was just used as visible indicator of molybdenum diffusion through alumina pellets. However, susbstitution of hydrazine sulfate as reducing agent by citric acid for Mo-blue formation has been proposed [39] due to its extreme toxicity and carcinogenicity that makes impractical its utilization. Interestingly, Srinivasan et al [38] failed in obtaining Mo-blue by using sucrose as reducing agent eve after heating at 373 K heating.…”

Cholesterol, Lipid Content, and Fatty Acid Composition of Different Tissues of Farmed Cobia (Rachycentron canadum) from China

“…The standard stock and working solutions were prepared according to the AOCS Official Method (method Ca 12-55) [21,22]. Depending on the level of phosphorus in the sample, a standard curve was established from the series with 0.000, 0.001, 0.002, 0.003, 0.004, 0.005, and 0.006 mg phosphorus.…”

Hydroxyapatite Nanocoating on Calcium Peroxide Microparticles for Sustained Oxygen Release

“…Since SEM-EDX measurements suggested PB concentration-dependent HAp formation, the amount of phosphorus on the surface of CaO 2 was quantitatively evaluated using the molybdenum blue method ,, (Figure g). HAp-CaO 2 was dissolved in 1 N HCl [Ca 10 (PO 4 ) 6 (OH) 2 + 8H + → 10Ca 2+ + 6HPO 4 2– + 2H 2 O] and then the amount of dissolved phosphorus ions was measured.…”

“…The amount of phosphorus in CaO 2 was quantitatively evaluated using the molybdenum blue method as previously reported. , HAp-CaO 2 was prepared by immersing 3 mg of CaO 2 in 3 mL of 100 and 500 m M PB (1 mg mL –1 ) for 1 h at 37 °C. After washing three times by MilliQ, HAp-CaO 2 was completely dissolved in 3 mL of 1 N HCl for 1 h. As a control sample, 3 mg of uncoated CaO 2 was also dissolved in 3 mL of 1 N HCl.…”